Assessing the Impacts of Future Climate Change on Peak Flows in a Forested Watershed

Author(s): Dakhlalla, A.; Parajuli, P.

Future climate changes, such as precipitation, temperature, and carbon dioxide (CO2) can have dramatic impacts on the hydrological cycle. These climatic changes can also increase the intensity and occurrence of peak flow events, which cause significant damage to agriculture and infrastructure. This study was conducted in the Lower Pearl River Watershed (LPRW) in southern Mississippi, which is dominated by forests and is characterized by its high peak flows. The Soil and Water Assessment Tool (SWAT) was utilized to assess the impact of future climate change scenarios on peak flow frequency and magnitude.

The SWAT model was calibrated and validated for streamflow at five United States Geological Survey (USGS) gage stations (Bogalusa, Columbia, Monticello, Hanging Moss Creek, and Jackson) with good model performance based on the coefficient of determination, Nash-Sutcliffe Efficiency index, and root mean square error statistics. Future climate change scenarios were based on adjusting precipitation, temperature, and CO2 values. Observed daily precipitation and temperature data for the years 1981 to 2010 were used as inputs in a stochastic weather generator model to generate future climate data with the same statistical characteristics as the observed data. The occurrences and magnitudes of extreme peak flow events in the LPRW were analyzed under each climate scenario by developing flood hydrographs. Employing climate scenarios will aid in determining which climatic parameters have the most and least influence on peak flow magnitude and frequency. This study is expected to help in implementing best management practices (BMPs) more effectively in the LPRW that serve to attenuate peak flows.

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